If you're over 21, you usually can't enter. But if you're 22-25 and at college, you can. (speshul privleges.)
Theirs isn't the clearest wording, but I can't think of clearer way. "Or" still works best.

edit: I just shouldn't post in this thread. I get the wrong thread, I post too late, I don't read all the responses. it's like a curse.